Supporting device for an elongated magnetic-focussing type tube



April 1966 susuMu YASUDA ETAL 3,244,920

SUPPORTING DEVICE FOR AN ELONGATED MAGNETIC-FOCUSSING TYPE TUBE Filed Dec. 11, 1962 F/GJ. 45 /4O l 4/ 42; /7 I :23

44 4 nventor 5, IAsupA 4 ATA A Home y United States Patent 3,244,920 SUPPORTING DEVICE FOR AN ELONGATED MAGNETIC-FOCUSSiN G TYPE TUBE Susumu Yasuda and Hiroshi Hata, Minato-ku, Tokyo, Japan, assignors to Nippon Electric Company, Limited, Tokyo, Japan, a corporation of Japan Filed Dec. 11, 1962, Ser. No. 243,921 Claims priority, application Japan, Jan. 30, 1962, 37/ 3,447 4 Claims. (Cl. 313-50) placing it into a conjugately shaped coaxial hole in a radiator attached to the collector end portion of the magnetic focussing device) and the electron-gun end is adjustably supported by means of screws and resilient substance attached to this end portion of the magnetic focussing device.

a The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing in which:

, FIGS. 1 and 2 illustrate, in schematic axial sections,

conventional supporting devices for long electron beam focussing. device, the effective. longitudinal axis of the tube must be in precise concert with the axis of the magnetic focussing device in order to correctly guide the electron beam. Where this is accomplished the current transmission factor of the tube, or the collector-emission current ratio, is maximized.

One of the conventional supporting devices comprises a radiator coaxially attached to the magnetic focussing device on the collector end; a supporting member concentrically attached to the magnetic focussing device at the opposite or electron-gun end; a cup-shaped supporting piece'coaxially attached, by means of an adhesive, to the tube on the electron-gun end; and a plurality of adjusting screws which couple the supporting member and supporting piece in a variable manner. In another conventional supporting device, longitudinally spaced annular protrusions are provided around the tube envelope and form a snug fit to the inner surface of the magnetic focussing device.

These two devices, however, have inherent disadvanta'ges. In the former the initial adjustment is not only difficult (as will be explained in the following) but is hazardous to the tube in that excessive current is liable to flow in an intermediate electrode (the helical electrode, for example) either shortening its life or burning it out completely. Moreover the electron gun may be inadvertently moved, by the adjustment, beyond the allowable range, resulting in a mechanical rupture of the tube. The latter device is objectionable because of the precise machining that must be performed upon the annular protrusions; the fact that a fine adjustment of the effective axis of the tube is extremely diflicult; and the fact that the tube is very susceptible to external mechanical shock.

Hence the object of this invention is to provide a supporting device for an electron tube, utilizing a long electron beam, which allows a simple, safe and precise aligning of the aforementioned axes.

Briefly the apparatus according to the invention provides a supporting device wherein the collector end. of the tube is supported in the conventional manner (by magnetic-focussing type tubes.

FIG. 3 shows, in a similar view, the supporting device of the invention for the above type tube.

In order to lay aproper foundation for an explanation of the invention, two conventional devices used in conjunction with travelling-wave tubes will first be discussed with reference to FIGS. 1 and 2. In FIG. 1, the end of the travelling-wave tube 11 that is on the side of a collector 12 is supported by placing the collector into a hole 15 in the. hub of a radiator 14. The radiator is coaxially and integrally attached to the magnetic focussing device 13 at the corresponding end thereof. At the opposite, or electron-gun end 16 of the tube, a cup-shaped supporting piece .20, coaxially attached through an adhesive layer'19 to the end surface 18 of the envelope 17, is supported through adjusting screws 22 by a cylindrical flanged member 21 which is coaxially attached to the corresponding end portion of the magnetic focussing device 13. The inside surface of the hole 15, in the hub of the radiator, is conical and machined for tight fit to the outside, surface of the collector 12 so that the generated heat may be efficiently dissipated by the radiating fins 23. The collector is connected to a high-tension power source via .nut 24. At the opposite end of the adjusting screws, three or four in number, are spaced about the cylindrical member 21 and effect a radially adjustable engagement therewith. The initial adjustment is performed by impressing the required voltages on the electrodes of the tube and adjusting the radial position of the electron-gun end with the screws so that the current transmission factor becomes as large as possible. It is therefore all too possible with this supporting device for the electron-gun end of the travelling-wave tube to be inordinately displaced when the tube is initially inserted in the radiator hub, resulting in an intermediately disposed electrode, such as the helical electrode. 25, being excessively overloaded upon the application of the electrode voltages. Further, since the outside surface of the collector 12 fits snugly in the inside surface of the radiator hub, it may be seen that, with the arrangement at the electron-gun end, the strain upon the envelope during adjustment may be considerably more than its elasticity would hear. Moreover, the troublesome initial adjustment must be repeated every time the travelling-wave tube is replaced.

Referring now to FIG. 2 (where similar nomenclature denotes similar parts), the conventional supporting device shown therein comprises annular protrusions 31, 31', and 31" which are provided around that portion of the travelling-wave tube envelope which surrounds the slow-wave structure 25. The outside surfaces of the protrusions fit snugly in the inner surface 32 of the magnetic focussing device 13 and maintain the position of the tube vis-a-vis the focussing device. In order to reduce the moment arm efiect of the electron-gun portion on the protrusions, it is additionally supported by the sliding fit of a cup-shaped supporting piece 33 to the cylindrical flanged suporting member 21, attached to the magnetic focussing device. An adhesive layer 19 between the end of the tube 18 and the cup-shaped piece maintains the relative position ofthese two members and effectively. secures the. sliding fit. The dificultyinherent in. machining these protrusions for, snug. fit is obvious. The fact that these'protrusions must be remachined. fora fine adjustment of the current transmission factors, or alignment of axes, adds a considerable disadvantage. Moreover, because of the fact that the magnetic focussing device and the tube are contiguous at the protrusions, any external shock is transmitted directly to the tube. It is to' be further noted that an excessive strain would develop in the tube if the coaxial relationship between the outer surface of the collector 12,'the outer surface of the protrusions, and the inside sliding surface (contacting member. 21) of the cup-shaped supporting piece is not maintained within the allowableflex-ibility of the envelope.

Referring now to FIG. 3, the electron tube. supporting device of the invention will be described. Again, like numerals refer to like parts of FIGS. 1 and 2. It may be seen that the structural support for the collector end of the tube is unchanged. On the electron-gun .side, however, the cylindrical flanged member 41, which is coaxially attached to the magnetic focussing device 13, is extended so that. it may encompass the end of the tube (although, as-will be seen, this is not absolutely necessary, it does provide protection for the more vulnerable envelope). The member 41' is'provided with fine-threaded holes 42 circumferentially spaced on a portion surroundingthe electron gun. An annular metal ring 44, dimensioned for a sliding fit, is disposed contiguous the inside cylindrical surface of the supporting member 41' and is attached through a layer 43' of sufficiently resilient substance to that portion 17 of the travelling-wavetube which circumscribes the electron gun. Although many resilient substances would s'ufiice, favorable'results have been obtained by molding a mixture of 100 parts by weight of silicone rubber (suchas, for example, Dow Cornings Silatex RTVSOl) and 4 parts by weight'of a curing agent (such as, for example, Dow Cornings Silicone Catalyst A)' in' a form which preferably has substan: tially the same shape as the cylindrical space between the internal surface of the supporting member 41 and the external surface of the portion 17; and then leaving it in the air, to solidify. By choosing the radial dimension of a first portion of the mold is substantially the same as,

or preferably slightly greater than, the radial dimension 7 of the above-mentioned cylindrical space, the first portionof layer 43' of resilient substance serves .to elastically maintain the relative positions of themetal 44 and the portion 17 surrounding the electron gun. If preferred, the first :portion of layer 43 and the ring 44 (or thepon tion 17 may be attached to eachother by an adhesive. Although the first portion of layer 43 has been described as taking a circumferentially continuous cylindrical form, this is not a requisite, and they outer or inner surface may be knurled, ridged, etc.

It is-now possible by means of adjusting screws 45, which engage withthe threaded holes 42 (longitudinally displaced from the ring), to. makethe effective axis of the travelling-wave tube coincide as precisely as possible with the axis ofthe magnetic-focussing device. It is to be remembered that these axes approximately coincide before adjustment by virtue of the sliding ,fit between the supporting member 41 and the metal ring 44. To

ensure that the relatively small screw ends do not cut through the soft" second or cut portion 47 of layer 43, larger area metal pieces 46, which may be bent to conform with the circumference of the cut or second portion of layer 43, are attached to either the screws or the contact areas on the circumference. The cut portion 47, which is not absolutely necessary, has been included in the resilient substance to reduce the strain thereon.

It may be seen that with the electron tube supporting device of the invention, it is possible to easily mount the tube in the magnetic focussing device by merely sliding it in the open end, opposite the radiator. By subsequently measuringthe current transmission factor with voltages impressed on the respective electrodes, it is possible by finely adjusting the screws to make the effective axis of the travelling-wave tube precisely coincide with the axis of the magnetic focussing device. The resilient portions of layer 43 serves several functions. During the fine adjustment, the firstportion of layer 43 restricts the relative radial displacement of the tube and focussing device, ensuring against an overstressingof the envelope. Layer 43 offers protection against. burning out an intermediateelectrode because of its restriction on adjustments. The second portion of layer 43 being intermediate the tube and focussing-idevice also guards the tube from an external mechanical shock.

It bears mentioning that-the resiliency of the first and second portions of layer 43- may be varied, and depends upon the material selected and its unrestricted dimensions. Where practical, and this will generally be in a tube where the collector heat is such that it does not require a radiator; the device according to the invention may be utilized at both ends of the tube.

While we have described above the principles of our invention in connectionwith.specific'apparatus, it is to be clearly. understood that this description is made only by way of example and notas a limitation to. the scope of our invention as set forth in 'the objectsthereof and in the accompanying claims.

Whatis claimed is:

LA supporting arrangement for axially aligning an electron tube of the long electronbeam type and the magnetic device employed inconjunetion therewith for focus sing the long beam, comprising first and second means for supporting said tube relative said'focussing device at the electronv gun and collector ends thereof, respectively, said firstmeans comprising a cylinder integrally attached tosaidjfocussing device and disposed about the electron gun end of the tube, a layer of resilient material disposed between said. cylinder and the facing tube portion, and resilient adjusting means coupling said cylinder and said electrongun end of said tube forresiliently varying the relative position of the cylinder and tube at the electron gunend.

2. A supporting arrangement for axially aligning an electrontube of. the long electron beam type and the magnetic device employed in conjunctionherewith for focus sing the long beam, comprising first and second means for supporting'said tube relative said focussing device at the electron gun and collector ends thereof respectively, said first means comprising a cylinder integrally attached to said. focussing device and disposed about the electron gun end of the tube, a ring in said cylinder dimensioned for a slideable fit therein, a first portion of resilient material contained Within said ring, said first portion having an external unrestricted dimension at least as great as said ring and. an internal dimension substantially equal to that of the external dimension of the juxtaposed tube portion at the electron gun end, a second portion of resilient material disposed around said electron gun end of said tube and adjacent said first portion and resilient adjusting means coupling, said second portion and cylinder for varying the relative position of the cylinder and tube at the electron gun end.

3. A supporting arrangement as claimed in claim 2 wherein said resilient adjusting means comprises a plurality of screws spaced about the periphery of said cylinder and passing through tapped holes provided therefor, the holes in said cylinder being located to allow contact between the screw end and said second portion.

4. A supporting arrangement as claimed in claim 3 wherein larger area metal pieces are provided between said screw ends and said second portion for avoiding puncture of said second portion.

References Cited by the Examiner UNITED STATES PATENTS 2,984,762 5/1961 Haas 3154.5

5 FOREIGN PATENTS 845,000 8/1960 Great Britain.

GEORGE W. WESTBY, Primary Examiner.

10 ROBERT SEGAL, Examiner.

R. JUDD, Assistant Examiner. 

1. A SUPPORTING ARRANGEMENT FOR AXIALLY ALIGNING AN ELECTRON TUBE OF THE LONG ELECTRON BEAM TYPE AND THE MAGNETIC DEVICE EMPLOYED IN CONJUCTION THEREWITH FOR FOCUSSING THE LONG BEAM, COMPRISING FIRST AND SECOND MEANS FOR SUPPORTING SAID TUBE RELATIVE SAID FOCUSING DEVICE AT THE ELECTRON GUN AND COLLECTOR ENDS THEREOF RESPECTIVELY, SAID FIRST MEANS COMPRISING A CYLINDER INTEGRALLY ATTACHED TO SAID FOCUSSING DEVICE AND DISPOSED ABOUT THE ELECTRON GUN END OF THE TUBE, A LAYER OF RESILIENT MATERIAL DISPOSED BETWEEN SAID CYLINDER AND THE FACING TUBE PORTION, AND RESILIENT ADJUSTING MEANS COUPLING SAID CYLINDER AND SAID ELECTRON GUN END OF SAID TUBE FOR RESILIENTLY VARYING THE RELATIVE POSITION OF THE CYLINDER AND TUBE AT THE ELECTRON GUN END. 